kairos/trie.c

/*
 * trie.c: Trie implementation for storing values
 */

#include <string.h>
#include <syslog.h>
#include <stdio.h>

#include "trie.h"
#include "config.h"

static struct trie *trie_base;

static int indexof(char c) {
	// ASCII only!
	if ('A' <= c && c <= 'Z') {
		return (c - 'A');
	} else if ('0' <= c && c <= '9') {
		return (c - '0' + 26);
	} else if (c == '_') {
		return 36;
	} else {
		// Something weird happened
		syslog(cfg_log_facility|LOG_ERR, "trie: weird input character: %c", c);
		return -1;
	}
}

static bool trie_set_deep(char string[], int64_t val, struct trie *vertex) {
	// Recursive function to find and set a value
	if (string[0] = '\0') {
		vertex -> val = val;
		vertex -> defined = true;
		return true;
	} else {
		int chld_index = indexof(string[0]);
		if (chld_index == -1) {
			return false; //and don't save anything
		} else if (vertex -> children[chld_index] == NULL) {
			vertex -> children[chld_index] = (struct trie *) calloc(1, sizeof(struct trie));
			if (vertex -> children[chld_index] == NULL) {
				syslog(cfg_log_facility | LOG_ERR, "trie: could not allocate space: %m");
				return false;
			}
		}
		return trie_set_deep(string+1, val, vertex->children[chld_index]);
	}
}

bool trie_set(char string[], int64_t val) {
	if (trie_base == NULL) {
		trie_base = (struct trie *) calloc(1, sizeof(struct trie));
		if(trie_base == NULL) {
			syslog(cfg_log_facility | LOG_ERR, "trie: could not allocate any space: %m");
			return false;
		}
	}
	return trie_set_deep(string, val, trie_base);
}

static struct trie_retval trie_lookup_deep(char string[], struct trie *vertex) {
	if (string[0] == '\0') {
		return (struct trie_retval) {vertex -> val, vertex -> def};
	} else {
		int chld_index = indexof(string[0]);
		if (chld_index == -1 || vertex -> children[chld_index] == NULL) {
			return (struct trie_retval) {0, false};
		} else {
			return trie_lookup_deep(string + 1, vertex->children[chld_index]);
		}
	}
}

struct trie_retval trie_lookup(char string[]) {
	if (trie_base == NULL) {
		return (struct trie_retval) {0, false};
	} else return trie_lookup_deep(string, trie_base);
}

bool trie_load(void) {
	FILE *f = fopen(cfg_trie_file, "r");
	if (f == NULL) {
		syslog(cfg_log_facility | LOG_WARNING, "trie: could not load trie from file: %m");
		return false;
	}

	//FIXME: This is bad.
	int64_t val;
	char name[cfg_var_name_max_len+1];
	int status;
	while ((status = fscanf(f, "%s %d\n", name, &val)) != EOF) {
		if (status != 2) {
			syslog(cfg_log_facility | LOG_ERR, "trie: fscanf matched bad number of items: %d", status);
			return false;
		}
		if(trie_set(name, val) == false) {
			syslog(cfg_log_facility | LOG_WARN, "trie: setting a variable failed: %s = %d", name, val);
		}
	}
	return true;
}

bool trie_save(void) {
	FILE *f = fopen(cfg_trie_file, "w");
	if (f == NULL) {
		syslog(cfg_log_facility | LOG_CRIT, "trie: could not open file to save trie in: %m");
		return false;
	}

	// DFS, write every found variable into f
	
}